检索结果-南通市图书馆

A Quick Calculation Method for Radiation Pattern of Submillimeter Telescope with Deformation and Displacement

Research in Astronomy and Astrophysics 2024年第3期24卷 249-265页

作者： Jia You Yi-Wei Yao Zheng Wang school of Automation Southeast UniversityNanjing 210096China

Radiation pattern captures the electromagnetic performance of reflector antennas,which is significantly affected by the deformation of the primary reflector due to gravity and the displacement of the secondary *** the design process of large reflector antennas,a substantial amount of time is often dedicated to iteratively adjusting structural parameters and validating electromagnetic *** improve the efficiency of the design process,we first propose an approximate calculation method of optical path difference(OPD)for the deformation of the primary reflector under gravity and the displacement of the secondary *** an OPD fitting function based on the modified Zernike polynomials is proposed to capture the phase difference of radiation over the aperture plane,based on which the radiation pattern will be obtained quickly by the aperture field integration *** experiments demonstrate the effectiveness of the proposed quick calculation method for analyzing the radiation pattern of a 10.4 m submillimeter telescope antenna at its highest operating frequency of 856 *** comparison with the numerical simulation method based on GRASP(which is an antenna electromagnetic analysis tool combining physical optics(PO)and physical theory of diffraction(PTD)),the quick calculation method reduces the time for radiation pattern analysis from more than one hour to less than two ***,the quick calculation method exhibits excellent accuracy for the figure of merit(FOM)of the radiation ***,the proposed quick calculation method can obtain the radiation pattern with high speed and *** to the time-consuming numerical simulation method(PO and PTD),it can be employed for quick analysis of the radiation pattern for the lateral displacement of the secondary reflector and the deformation of the primary reflector under gravity in the design process of a reflector antenna.

关键词： instrumentation high angular resolution-methods data analysis-methods analytical

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Investigation of non-uniform leading-edge tubercles in compressor cascade:Based on multi-objective optimization and data mining

引用

Chinese Journal of Aeronautics 2024年第7期37卷 134-152页

作者： Jiezhong DONG Wuli CHU Haoguang ZHANG Bo LUO Tianyuan JI Ziyun ZHANG school of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China

Corner stall receives noticeable attention in the aeroengine field as an important phenomenon in highly-load ***-uniform leading-edge tubercles,as an effective method to delay stall,are introduced into the *** this paper,the shape of leading-edge tubercles was controlled by a third-order Fourier *** judge corner stall,a more precise stall indicator for compressor cascade with flow control methods was ***,the total kinetic energy of the secondary flow at large incidence was adopted as a parameter for stall evaluation to save computing *** results of multiobjective optimization reveal that the loss coefficient exhibited negligible variation at design incidence,while the total kinetic energy of secondary flow showed a significant reduction at large incidence,resulting in a substantial increase in stall *** the optimal profiling cases,the stall incidencewas delayed from 7.9°to 11.6°.The major purpose of the research is to provide proper design guidelines for nonuniformleading-edge tubercles and uncover the flow controlmechanisms of leading-edge ***,the geometric features that meet different optimization objectives were extracted through geometric analysis near the Pareto Front and through Self-OrganizingMap(SOM)dataminingmethods in the optimization ***,flow field analysis reveals the flow control mechanism of leading-edge *** convex-concave-convex structure at the 0%-70%blade height region can form two branches of leading-edge vortex pairs that are opposite in the rotation direction to the passage *** two branches of leading-edge vortex pairs mixed with the leading-edge separation vortex to form two stronger mixed vortices,which can effectively suppress the development of passage vortex and delay stall incidence.

关键词： Corner stall Non-uniform leading-edge tubercles Stall indicator Stall evaluation parameter Mixed vortex

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Impacts of electrochemical disinfection on the viability and structure of the microbiome in secondary effluent water

引用

Frontiers of Environmental Science & Engineering 2024年第5期18卷 73-83页

作者： Marvin Yeung Lan Tian Yuhong Liu Hairong Wang Jinying Xi Environmental Simulation and Pollution Control State Key Joint Laboratory School of EnvironmentTsinghua UniversityBeijing100084China Graduate school at Shenzhen Tsinghua UniversityShenzhen518055China

Electrochemical disinfection(ECD)is a promising disinfection technique for wastewater reclamation;however,the impacts of ECD on the microbiome in secondary effluent wastewater remain *** this study,Propidium monoazide-qPCR(PMA-qPCR)and the plate count method were used to evaluate the inactivation performance,and the PMA-16S rRNA gene sequences of living cells were targeted to study the microbiome.A discrepancy was found between PMA-qPCR and the plate count method in the evaluation of cell count,with increases of 1.5 to 2.2 orders of magnitude in the disinfection rate after 150 s of ***,the cell count recovered and occasionally exceeded original levels within 3 d after *** was suppressed after ECD,but the microbiome after 150 s disinfection retained a higher level of evenness and stability in the community with a median Shannon index(>3.7).Pathogenic bacteria remained high in relative abundance even after 150 s of 25 V disinfection,but the biofilm-forming population was effectively suppressed by *** co-occurrence network revealed a centralized and fragile network as disinfection persisted,demonstrating the destabilizing effects of ECD on the *** pathways for cell membrane synthesis and organic compound degradation were enriched after *** reaction of the microbiome after ECD was similar to other disinfection techniques in terms of community structure.

关键词： Electrochemical disinfection secondary effluent Microbiome

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Temperature dependence of mechanical properties and damage evolution of hot dry rocks under rapid cooling

引用

Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 645-660页

作者： Longjun Dong Yihan Zhang Lichang Wang Lu Wang Shen Zhang school of Resources and Safety Engineering Central South UniversityChangsha410083China school of Geosciences and Info-physics Central South UniversityChangsha410083China

Understanding the differences in mechanical properties and damage characteristics of granitoid under high temperatures is crucial for exploring deep geothermal *** study analyzes the evolution of the acoustic emission(AE)characteristics and mechanical parameters of granodiorite and granite after heating and water cooling by uniaxial compression and variable-angle shear tests under different temperature *** identify their changes in mesostructure and mineral composition with electron probe microanalysis and scanning electron *** show that these two hot dry rocks have similar diagenetic minerals and microstructure,but show significantly different mechanical and acoustic characteristics,and even opposing evolution trends in a certain temperature *** the temperatures ranging from 100℃to 500℃,the compressive and shear mechanical properties of granodiorite switch repeatedly between weakening and strengthening,and those of granite show a continuous weakening *** 600℃,both rocks exhibit a deterioration of mechanical *** damage mode of granite is characterized by initiating at low stress,exponential evolutionary activity,and intensified energy *** contrast,granodiorite exhibits the characteristics of initiating at high stress,volatile evolutionary activity,and intermittent energy release,due to its more stable microstructure and fewer thermal defects compared to *** the temperature increases,the initiation and propagation of secondary cracks in granodiorite are suppressed to a certain extent,and the seismicity and brittleness are *** subtle differences in grain size,microscopic heterogeneity,and mineral composition of the two hot dry rocks determine the different acoustic-mechanical characteristics under heating and cooling,and the evolution trends with *** findings are of great significance for the scientific and efficient construction of rock mass engineering by rationally utilizin

关键词： Hot dry rock Acoustic emission Mechanical properties High temperature Damage

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

S-scheme heterojunction in photocatalytic hydrogen production

引用

Journal of Materials Science & Technology 2024年第2期169卷 82-104页

作者： Teng Li Noritatsu Tsubaki Zhiliang Jin school of Chemistry and Chemical Engineering North Minzu UniversityYinchuan 750021China Department of Applied Chemistry Graduate School of EngineeringUniversity of ToyamaGofuku 3190Toyama 930-8555Japan

As an ideal secondary energy source,hydrogen has the title of clean energy and the product of its complete combustion is only water,which is not polluting to the *** hydrogen production technology is an environmentally friendly,safe,and low-cost strategy that requires only an inexhaustible amount of solar energy and water as *** paper provides a detailed and detailed review of S-scheme heterojunction photocatalysts for photocatalytic hydrogen production,mainly including TiO_(2)-based,Perovskite-based,CdS-based,Graphitic phase carbon nitride-based,COF-based graphdiyne-based,ZnO-based,and ZnIn_(2)S_(4)-based S-scheme heterojunction *** classification of S-scheme heterojunctions is ***’s more,various characterizations for direct verification of the charge migration mechanism of S-scheme heterojunctions are *** on the present study,the future potential challenges and future research trends for S-scheme heterojunctions in photocatalytic hydrogen evolution technology are pointed out,which provides feasible strategies for the development and design of S-scheme heterojunction photocatalysts in the field of photocatalytic hydrogen evolution.

关键词： S-scheme heterojunction Photocatalysis Charges migration Hydrogen evolution

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Multiple damage zones around hydraulic fractures generated by high-frequency pulsating hydraulic fracturing

引用

Petroleum Science 2024年第4期21卷 2688-2702页

作者： Yan Peng Sheng-Jie Wei Guang-Qing Zhang Da-Wei Zhou Chuang-Chao Xu school of Petroleum Engineering China University of Petroleum PetroChina Changqing Oilfield Company

Pulsating hydraulic fracturing(PHF) is a promising fracturing method and can generate a dynamic periodic pressure. The periodic pressure can induce fatigue failure of rocks and decrease initiation pressure of fracture. If the frequency of periodic pressure exceeds 10 Hz, the distribution of pressure along the main fracture will be heterogeneous, which is much different from the one induced by the common fracturing method. In this study, the impact of this special spatial feature of pressure on hydraulic fracture is mainly investigated. A coupled numerical simulation model is first proposed and verified through experimental and theoretical solutions. The mechanism of secondary fracture initiation around the main fracture is then discovered. In addition, sensitivity studies are conducted to find out the application potential of this new method. The results show that(1) this coupled numerical simulation model is accurate. Through comparison with experimental and theoretical data, the average error of this coupled model is less than 1.01%.(2) Even if a reservoir has no natural fracture, this heterogeneous distribution pressure can also cause many secondary fractures around the main fracture.(3) The mechanism of secondary fracture initiation is that this heterogeneous distribution pressure causes tensile stress at many locations along the main fracture.(4) Through adjusting the stimulation parameters, the stimulation efficiency can be improved. The average and amplitude of pressure can increase possibility of secondary fracture initiation. The frequency of this periodic pressure can increase number of secondary fractures. Even 6 secondary fractures along a 100 m-length main fracture can be generated.(5) The influence magnitudes of stimulation parameters are larger than ones of geomechanical properties, therefore, this new fracturing method has a wide application potential.

关键词： Tight reservoir Reservoir stimulation Numerical simulation secondary fracture Fracture initiation

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Distributed Cooperative secondary Voltage Control in an Unbalanced Microgrid

引用

CSEE Journal of Power and Energy Systems 2024年第1期10卷 222-234页

作者： Xiangzhen Yang Haixi Zhao Mengke Duan Yan Du Haining Wang Jian Zhang school of Electrical Engineering and Automation Hefei University of TechnologyHefei 23009China

The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded ***, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop *** this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each *** algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance ***, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.

关键词： Distributed cooperative control MG negativesequence reactive power starsim real-time platform time delay voltage unbalance compensation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Study on Local Flow and Heat Transfer Characteristics of Supercritical CO_(2) in PCHE with Sinusoidal Channels

引用

Journal of Thermal Science 2024年第1期33卷 41-55页

作者： WENZhexi LV Yigao LI Qing WU Jinglin school of Energy Science and Engineering Central South UniversityChangsha 410083China

Local heat transfer and flow characteristics,which is crucial to the overall performance of supercritical CO_(2) recuperators,is rarely examined in details in reported *** this paper,the local heat transfer and flow characteristics of supercritical CO_(2) in sinusoidal channel printed circuit heat exchangers are numerically investigated under the working conditions of *** on the simplified physical model constituted by10 pitches,the variations of Re,heat flux,Nu,secondary flow and other relevant parameters along the flow direction are analyzed *** is further made between the high and low temperature recuperators(HTR and LTR).It's observed that the local heat transfer and flow characteristics vary greatly from the inlet to the outlet,especially in the *** of 127.5% and 61.7% can be observed on the cold side of the LTR for Re and heat transfer coefficient h, *** indicate that the temperature difference and heat transfer coefficient h should not be regarded as constant and the distribution of h should be carefully considered in the design of the *** complicated interactions among the varying thermophysical properties,buoyancy and the periodically changed centrifugal force are believed to be the key that shapes the flow ***,the changes of the wavy angle θ are found to have greater influence than the changes of mass flow rate in reshaping the flow field when θ>25°.Though gravity direction strongly affects the local heat transfer and flow characteristics,it's also found that the effects on the overall thermal-hydraulic performance are relatively *** the installation direction that yields a_y=g should better be avoided for the sinusoidal channel printed circuit heat exchanger.

关键词： printed circuit heat exchanger supercritical CO_(2) sinusoidal channel heat transfer recuperator

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recyclable Technology of Thermosetting Resins for High Thermal Conductivity Materials Based on Physical Crushing

引用

Energy & Environmental Materials 2024年第6期7卷 378-387页

作者： An Zhong Congzhen Xie Bin Gou Jiangang Zhou Huasong Xu Song Yu Daoming Zhang Chunhui Bi Hangchuan Cai Licheng Li Rui Wang school of Electric Power South China University of TechnologyGuangzhou 510641China

Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic ***,the efficient recycling and reuse of epoxy materials with thermally cross-linked molecular structures has become a daunting ***,we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high-performance *** particle size of waste epoxy micro-spheres(100–600μm)with core-shell structure is obtained through simple mechanical crushing and boron nitride surface *** using smattering epoxy monomer as an adhesive,an eco-friendly composite material with a“brick-wall structure”can be *** continuous boron nitride pathway with efficient thermal conductivity endows eco-friendly composite materials with a preeminent thermal conductivity of 3.71 W m^(−1)K^(−1)at a low content of 8.5 vol%h-BN,superior to pure epoxy resin(0.21 W m^(−1)K^(−1)).The composite,after secondary recycling and reuse,still maintains a thermal conductivity of 2.12 W m^(−1)K^(−1)and has mechanical and insulation properties comparable to the new epoxy resin(energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm^(−1)).This strategy expands the sustainable application prospects of thermosetting polymers,offering extremely high economic and environmental value.

关键词： brick-wall structure epoxy thermosetting physical recycling thermal management

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Single and combined effects of secondary polyethylene microplastic on the growth of Pak choi and the soil microbiome composition

引用

Frontiers of Environmental Science & Engineering 2024年第5期18卷 1-12页

作者： Jiamin Hu Zhenwen Xie Jiane Zuo State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China Tsinghua Shenzhen International Graduate school Tsinghua UniversityShenzhen518055China

It has been confirmed that microplastics(MPs)are present in the *** study simulated secondary PE-MPs via aging and mechanical processes to evaluate their effects on Pak choi(Brassica rapa L.)over 21 *** common pollutants,dichlorodiphenyltrichloroethane(DDT)and naphthalene,were used in the combined toxicity *** results indicated that the growth of Pak choi was significantly inhibited after exposure to secondary PE-MPs,and the combined effects were antagonistic,owing to the adsorption capacity of secondary PE-MPs to DDT and *** stress in Pak choi can be markedly affected,leading to oxidative damage to plant *** moisture content,soil bulk density,soil density,cation exchange capacity(CEC),and FDA hydrolase in the planted soils increased in the treated groups,and the TOC content changed *** also found that the microbial composition of the soil in the DDT and naphthalene groups showed more significant alterations than that in the other *** diversity analysis showed that species diversity increased in the combined groups but indicated a clear downward trend in the single MPs *** study suggests that secondary PE-MPs harm the growth of Pak choi and can change soil properties,revealing the harm to the ecosystem of MPs in the soil.

关键词： secondary PE-MPs Combined effects Oxidative stress Soil properties Bacterial community

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：